Caviomorpha is the rodent infraorder or parvorder that unites all New World hystricognaths. It is supported by both fossil and molecular evidence. The Caviomorpha was for a time considered to be a separate order outside the Rodentia, but is now accepted as a genuine part of the rodents. Caviomorphs include the extinct Heptaxodontidae, the extinct Josephoartigasia monesi and extant families of chinchilla rats, hutias, guinea pigs and the capybara, chinchillas and viscachas, tuco-tucos, agoutis, pacas, pacaranas, spiny rats, New World porcupines, coypu and octodonts.
Akodon is a genus consisting of South American grass mice. They mostly occur south of the Amazon Basin and along the Andes north to Venezuela, but are absent from much of the basin itself, the far south of the continent, and the lowlands west of the Andes. Akodon is one of the most species-rich genera of Neotropical rodents. Species of Akodon are known to inhabit a variety of habitats from tropical and tropical moist forests to altiplano and desert. Fossils are known from the late Pliocene onwards.
Chinchilla rats or chinchillones are members of the family Abrocomidae. This family has few members compared to most rodent families, with only nine known living species. They resemble chinchillas in appearance, with a similar soft fur and silvery-grey color, but have a body structure more like a short-tailed rat. They are social, tunnel-dwelling animals, and live in the Andes Mountains of South America. They are probably herbivorous, although this is not clear.
Oxymycterus is a genus of rat-like rodents commonly known as hocicudos. They are endemic to South America. As of April 2019, the genus contains the following 16 species:
The Asháninka arboreal chinchilla rat is a large species of chinchilla rats from the Andes of far northern Cusco in Peru. It was first scientifically described in 1999.
Cuscomys is a genus of rodents found in the Andes of Cusco in southern Peru. These relatively large chinchilla rats are dark grey with a distinct white line running from the crown to the nose. The genus was coined in 1999 when C. ashaninka was scientifically described, but later it was discovered that C. oblativus, a species traditionally placed in the genus Abrocoma, actually belonged in Cuscomys. They are very poorly known, as C. ashaninka only is known from the holotype, while C. oblativus usually has been considered extinct, as it was only known from remains found in 1912, buried alongside people in ancient Inca tombs at the Machu Picchu ruins. However, photos of a rodent taken at the ruins in late 2009 likely show this species. It is unclear if the Cuscomys truly are extremely rare, as they may be easily overlooked due to their remote distributions and arboreal habits.
The Machu Picchu arboreal chinchilla rat is a large species of South American chinchilla rats, known from skeletal remains found by members of the Peruvian Expedition of 1912. The animals were buried alongside people in ancient Inca tombs at Machu Picchu in Peru. It was considered extinct by the IUCN in 2008, but conservation status was changed to data deficient in 2016. Photos of a rodent taken at Machu Picchu in late 2009 likely show this species, a finding apparently confirmed in 2014.
Bennett's chinchilla rat is a species of chinchilla rat in the family Abrocomidae. It is found only in Chile where its habitat is Mediterranean-type scrub on the western side of the Andes. The IUCN has assessed its conservation status as being of "least concern".
The ashy chinchilla rat is a species of chinchilla rats in the family Abrocomidae found in Argentina, Bolivia, Chile, and Peru.
The mountain viscacha rat or mountain vizcacha rat, historically viscacha rat or vizcacha rat, is a species of rodent in the family Octodontidae. It is endemic to Argentina.
The plains viscacha rat, plains vizcacha rat, red viscacha rat, or red vizcacha rat is a species of rodent in the family Octodontidae native to Argentina. It is one of three species in the genus Tympanoctomys.
Budin's chinchilla rat is a species of chinchilla rat in the family Abrocomidae. Found only in Argentina, the categorization of this species was based on analysis of four specimens which were caught among the rocks in the clefts of which it lived. It is specifically known from Otro Cerro, Catamarca Province and known to occur in rocky areas over 3,000 meters above sea level; research shows it may be confined to Sierra de Ambato in Catamarca Province and La Rioja Province. In 2002, Braun and Mares from the University of Oklahoma examined this specimen and confirmed it to be a separate species. Not enough is known about this species for the IUCN to assess its conservation status.
The Famatina chinchilla rat is a species of chinchilla rats in the family Abrocomidae found only in Argentina.
The Sierra del Tontal chinchilla rat is a species of chinchilla rat. Found only in Argentina, this species was once thought to be part of Abrocoma cinerea. In 2002, Braun and Mares from the University of Oklahoma confirmed it to be a separate species.
The Uspallata chinchilla rat is a species of chinchilla rat in the family Abrocomidae native to Argentina. This species was identified in 2002, by Braun and Mares from the University of Oklahoma. Only a single specimen has been examined.
The Punta de Vacas chinchilla rat, also known as the Mendozan chinchilla rat, is a species of chinchilla rats in the family Abrocomidae. Found only in Argentina, this species was once thought to be part of Abrocoma cinerea. In 2002, Braun and Mares from the University of Oklahoma confirmed it to be a separate species.
Octodontidae is a family of rodents, restricted to southwestern South America. Fourteen species of octodontid are recognised, arranged in seven genera. The best known species is the common degu, Octodon degus.
The delicate salt flat mouse is a sigmodontine rodent species in the family Cricetidae from South America. It is the only species in the genus Salinomys. Its habitat is scrublands bordering salt flats in the Monte Desert area of central western Argentina at elevations around 400 m. The closest relatives of the species are the chaco mice (Andalgalomys).
